JP7526359B2 - Bottomed cylindrical body - Google Patents

Description

The present invention relates to a cylindrical body with a bottom.

Conventionally, optical probes are used to monitor industrial processes in harsh environments. Examples of such optical probes include optical pyrometers for measuring temperature and optical fiber spectrometers for measuring chemical composition. These optical probes are housed and protected in a sealed shroud. As such a shroud, Patent Document 1 describes a seal assembly for an optical sensor.

JP 2010-139503 A

The bottomed cylindrical body according to the present disclosure includes a cylindrical portion formed of ceramics mainly composed of aluminum oxide, and a flat window portion that seals at least one end of the cylindrical portion. The window portion is formed of sapphire or a transparent ceramic. The cylindrical portion and the window portion are joined together, and a first opposing surface of the window portion on the cylindrical portion side has a larger average value of the mean length (Rsm) in the roughness curve than a second opposing surface of the cylindrical portion on the window portion side. Furthermore, the seal assembly for an optical sensor according to the present disclosure includes the bottomed cylindrical body described above.

FIG. 2 is a perspective view showing a bottomed tubular body according to an embodiment of the present disclosure. FIG. 2 is an explanatory diagram showing a cross section taken along line XX shown in FIG. FIG. 1 is an explanatory diagram showing the crystal structure of sapphire.

As described above, conventional seal assemblies for optical sensors are composed of components made of materials with different linear expansion coefficients, such as platinum, nickel-based alloys, brazing material, glass, and sapphire. Therefore, when exposed to high temperatures for a long period of time, the sapphire is prone to distortion. If the distortion remains in the sapphire for a long period of time, it becomes difficult for the optical sensor to accurately detect information about the target object.

Therefore, there is a need for a bottomed cylindrical body that can accurately detect information about an object when an optical sensor is housed inside.

The bottomed cylindrical body according to the present disclosure has a large average value of the average length (Rsm) of the first opposing surface on the cylindrical portion side of the window portion. Therefore, the intervals (period) between the concave portions and between the convex portions of the first opposing surface are wide, and scattering is unlikely to occur even when visible light or near-infrared light is irradiated to the window portion. Therefore, the bottomed cylindrical body according to the present disclosure can accurately detect information about an object when an optical sensor is housed therein.

A bottomed tubular body according to one embodiment of the present disclosure will be described with reference to Figures 1 and 2. The bottomed tubular body 1 according to one embodiment shown in Figure 1 includes a tubular portion 11 and a window portion 12 that seals at least one end of the tubular portion 11.

The cylindrical portion 11 included in the bottomed cylindrical body 1 according to one embodiment is formed of ceramics containing aluminum oxide as the main component. In this specification, the term "main component" refers to a component that is contained in an amount of 80% by mass or more when the total amount of the components constituting the ceramic is taken as 100% by mass. Each component contained in the ceramic is identified using an X-ray diffraction device using CuKα radiation, and the proportion of each component can be determined, for example, using an ICP (Inductively Coupled Plasma) emission spectrometer or an X-ray fluorescence analyzer.

The ceramics forming the cylindrical portion 11 may contain other components. Examples of the other components include sodium, magnesium, calcium, silicon, and nickel. These elements are usually contained as oxides. For example, it is preferable that at least a part of the sodium exists as sodium oxide ( _Na2O ), and that this sodium oxide exists more in the inner region of the grain boundary phase than in the boundary region with the aluminum oxide crystals.

If sodium oxide is present in greater amounts in the internal region than in the boundary region with the aluminum oxide crystals, the dielectric tangent is lower. Therefore, even when used in an environment where high-frequency voltage is applied, the heat generated is reduced. As a result, if an optical sensor is housed in the bottomed cylindrical body 1, thermal damage to the optical sensor can be reduced. Sodium may be contained in a ratio of, for example, 30 ppm by mass or more and 500 ppm by mass or less, calculated as sodium oxide.

The ceramics forming the cylindrical portion 11 may contain nickel in a proportion of 4 ppm by mass or less, calculated as nickel oxide (NiO). Nickel tends to vary in color depending on the degree of oxidation. However, if the nickel content is 4 ppm by mass or less, calculated as nickel oxide (NiO), color variation is less likely to occur.

The ceramics forming the cylindrical portion 11 may contain at least any one of elements of Groups 4, 5, and 6 of the periodic table in a total amount of 0.01% by mass or more and 1% by mass or less, calculated as oxides. When the total amount of these elements calculated as oxides is 0.01% by mass or more, sodium tends to exist as a composite compound such as _NaTiO3 , _NaZrO3 , _NaVO3 , _NaNbO3 , _NaTaO3 , _NaCrO3 , _NaMnO3 , and _NaWO3 . The chemical reaction formula is as follows:
_M2O5 + _Na2O → _2NaMO3 (M: elements of groups 4, 5 _, and 6 of the periodic table)

In this way, when sodium is present as a complex compound, sodium is inactivated, and the dielectric loss tangent can be reduced. For example, the dielectric loss tangent at a frequency of 8.5 GHz can be reduced to 2×10 ⁻⁴ or less. In particular, when the total content of these elements converted into oxides is 0.1 mass % or more, the dielectric loss tangent at a frequency of 8.5 GHz can be reduced to 1×10 ⁻⁴ or less.

On the other hand, if these elements are contained in large amounts as oxides, abnormal grain growth of aluminum oxide occurs, and mechanical properties are likely to deteriorate. However, if the total content converted to elements of Groups 4, 5, and 6 of the Periodic Table is 1 mass% or less, mechanical properties such as fracture toughness, static modulus of elasticity, and mechanical strength can be sufficiently maintained.

The ceramics forming the cylindrical portion 11 may contain magnesium in a ratio of 0.02% by mass or more and 0.7% by mass or less, calculated as magnesium oxide (MgO). If the magnesium is 0.02% by mass or more, calculated as magnesium oxide (MgO), the mechanical strength can be increased, and for example, the three-point bending strength can be made 250 MPa or more. Furthermore, to make the three-point bending strength 320 MPa or more, it is preferable to contain magnesium in a ratio of 0.1% by mass or more, calculated as magnesium oxide (MgO).

Magnesium usually exists as a solid solution in aluminum oxide or as magnesium aluminate after reacting with aluminum oxide. However, if magnesium oxide particles are present in excess in ceramics, the magnesium oxide particles may aggregate and become fracture origins, or may fall off during grinding or polishing, causing localized abnormalities on the opposing surfaces to be joined. If magnesium is 0.7 mass% or less, calculated as magnesium oxide (MgO), the above-mentioned fracture origins and localized abnormalities can be suppressed.

When the content of each element converted into its oxide is small, for example 0.1 mass% or less, it can be determined using a highly accurate glow discharge mass spectrometer (GDMS).

The size of the cylindrical portion 11 is not limited and is set appropriately depending on the application of the bottomed cylindrical body 1. For example, the cylindrical portion 11 has an outer diameter of 5.0 mm to 15.0 mm, an inner diameter of 1.0 mm to 13.0 mm, and a length in the axial direction of 30 mm to 150 mm.

The window portion 12 included in the bottomed cylindrical body 1 according to one embodiment seals at least one end of the cylindrical portion 11. The window portion 12 has a flat plate shape. The window portion 12 is made of sapphire or a transparent ceramic.

Sapphire is a single crystal of aluminum oxide (Al ₂ O ₃ ). Sapphire has excellent heat resistance, thermal conductivity, and heat dissipation, and also has the property of being able to suppress temperature rise. The transparent ceramics are not limited as long as they are ceramics that transmit light, and examples thereof include quartz and zircon. Furthermore, the transparent ceramics also include translucent ceramics defined in JIS R 1600:2011. The window portion 12 may have a light transmittance of, for example, 85% or more in the visible light region (wavelength region: 380 nm to 780 nm) and the near-infrared region (wavelength region: 780 nm to 1700 nm). The size and shape of the window portion 12 are not limited, and are appropriately set according to the size and shape of the cylindrical portion 11. The window portion 12 has a thickness of, for example, 0.2 mm to 2.0 mm.

When the window portion 12 is made of sapphire, it is preferable that the c-axis of the sapphire and the central axis of the cylindrical portion 11 are approximately parallel. Sapphire has anisotropy in thermal conductivity, and has high thermal conductivity in a direction parallel to the c-axis. If the c-axis of the sapphire and the central axis of the cylindrical portion 11 are approximately parallel, the thickness direction of the window portion 12 and the c-axis direction of the sapphire coincide with each other. As a result, the heat dissipation performance in the thickness direction of the window portion 12 can be improved. "Approximately parallel" means that the c-axis of the sapphire and the central axis of the cylindrical portion 11 do not necessarily have to be parallel, and the angle between the c-axis of the sapphire and the central axis of the cylindrical portion 11 is 5° or less.

We will explain the crystal planes of sapphire. Figure 3 shows the crystal structure of sapphire. As shown in Figures 3(A) to (D), sapphire has a hexagonal structure, with the c-plane, m-plane, a-plane, and r-plane being typical crystal planes. The axes perpendicular to these planes are called the c-axis, m-axis, a-axis, and r-axis, respectively.

There is no significant difference in linear expansion coefficient between the ceramics mainly composed of aluminum oxide forming the cylindrical portion 11 and the sapphire or translucent ceramics forming the window portion 12. Therefore, even if exposed to high temperatures for a long period of time, sapphire or translucent ceramics is unlikely to be distorted. As a result, for example, when an optical sensor is housed inside the bottomed cylindrical body 1 according to one embodiment, the optical sensor can accurately detect information about the target object even in an environment where it is exposed to high temperatures for a long period of time. Since sapphire is a single crystal of aluminum oxide, when the window portion 12 is made of sapphire, the difference in linear expansion coefficient between the cylindrical portion 11 formed of ceramics mainly composed of aluminum oxide approaches 0.

The bottomed cylindrical body 1 is a joint of a cylindrical portion 11 and a window portion 12. As shown in FIG. 2, in the opposing surfaces 13 between the cylindrical portion 11 and the window portion 12, that is, the first opposing surface 131 on the cylindrical portion 11 side of the window portion 12 and the second opposing surface 132 on the window portion 12 side of the cylindrical portion 11, the first opposing surface 131 has a larger average value of the average length (Rsm) in the roughness curve than the second opposing surface 132. The average length (Rsm) in the roughness curve was measured for each of the first opposing surface 131 and the second opposing surface 132 after the cylindrical portion 11 and the window portion 12 were joined. The average length (Rsm) of the first opposing surface 131 can be measured by cutting and thinning the cylindrical portion 11. The cylindrical portion 11 is cut to make it thinner in order to enable the objective lens to be brought closer to the first opposing surface 131 and to focus when measuring the average length (Rsm) using a shape analysis laser microscope described below.

On the other hand, when the window portion 12 is thick, for example, the thickness exceeds 0.1 mm, the average length (Rsm) of the second opposing surface 132 can be measured by polishing the window portion 12 from the opposite side to the first opposing surface 131 to make it thinner and transmitting laser light through the window portion. When laser light is irradiated onto the window portion 12, the laser light is slightly scattered by defects on the surface and inside. In order to reduce the effect of this scattering on the measured average length (Rsm), it is preferable to polish the window portion 12 until the thickness is 0.1 mm or less, and to set the arithmetic mean roughness Ra of the surface to 0.005 μm or less.

Because the average value of the average length (Rsm) in the roughness curve of the first opposing surface 131 is greater than the average value of the average length (Rsm) in the roughness curve of the second opposing surface 132, the interval (period) between the concave portions and the interval (period) between the convex portions of the first opposing surface 131 are wide. Therefore, even if visible light and near-infrared light are irradiated onto the window portion 12, scattering is unlikely to occur. As a result, for example, when an optical sensor is housed inside the bottomed cylindrical body 1 according to one embodiment, the optical sensor can accurately detect information about the target object.

Furthermore, since the average value of the average length (Rsm) in the roughness curve of the second opposing surface 132 is smaller than the average value of the average length (Rsm) in the roughness curve of the first opposing surface 131, the interval (period) between the recesses is narrow. As a result, when the cylindrical portion 11 and the window portion 12 are joined, the recesses are filled with glass components eluted from the cylindrical portion 11, etc., and sufficient joining strength is exerted.

The average value of the average length (Rsm) in the roughness curve of the second opposing surface 132 is not limited as long as it is smaller than the average value of the average length (Rsm) in the roughness curve of the first opposing surface 131. The average value of the average length (Rsm) in the roughness curve of the second opposing surface 132 may be, for example, 22.8 μm or less (excluding 0 μm). If the average value of the average length (Rsm) in the roughness curve of the second opposing surface 132 is in such a range, excellent bonding strength is exhibited when the tubular portion 11 and the window portion 12 are bonded to each other.

The average value of the average length (Rsm) in the roughness curve of the first opposing surface 131 is not limited as long as it is greater than the average value of the average length (Rsm) in the roughness curve of the second opposing surface 132. The average value of the average length (Rsm) in the roughness curve of the first opposing surface 131 may be, for example, 10 μm or more and 40 μm or less. If the average length (Rsm) in the roughness curve of the first opposing surface 131 is in such a range, even if visible light and near infrared rays are irradiated to the window portion 12, almost no scattering occurs. As a result, for example, when an optical sensor is housed inside the bottomed cylindrical body 1 according to one embodiment, the optical sensor can accurately detect information of the target object.

As long as the average value of the average length (Rsm) in the roughness curve of the first opposing surface 131 is greater than the average value of the average length (Rsm) in the roughness curve of the second opposing surface 132, the difference is not limited. For example, the difference between the average value of the average length (Rsm) in the roughness curve of the first opposing surface 131 and the average value of the average length (Rsm) in the roughness curve of the second opposing surface 132 may be, for example, 2.3 μm or more and 31 μm or less.

In the bottomed cylindrical body 1 according to one embodiment, the average value of the root mean square slope (RΔq) in the roughness curve of the second opposing surface 132 may be greater than the average value of the root mean square slope (RΔq) in the roughness curve of the first opposing surface 131. In such a case, the second opposing surface 132 has a high anchor effect on the first opposing surface 131. As a result, for example, even if the area of the second opposing surface 132 is narrower than the area of the first opposing surface 131, excellent bonding strength is exhibited. Furthermore, the first opposing surface 131 has fewer locally significantly inclined portions. Therefore, even if particles float in the internal space of the cylindrical portion 11, they are less likely to adhere to the first opposing surface 131. As a result, when contained inside the bottomed cylindrical body 1 according to one embodiment, the optical sensor can accurately detect information about the target object.

The root-mean-square slope (RΔq) of the roughness curve was measured for each of the first opposing surface 131 and the second opposing surface 132 after the cylindrical portion 11 and the window portion 12 were joined. The root-mean-square slope (RΔq) of the first opposing surface 131 can be measured by cutting and thinning the cylindrical portion 11. On the other hand, the root-mean-square slope (RΔq) of the second opposing surface 132 can be measured by polishing the window portion 12 from the opposite side of the first opposing surface 131 to make it thinner when the window portion 12 is thick, for example, when the thickness exceeds 0.1 mm, and transmitting laser light through the window portion 12.

In order to minimize the effect of slight scattering of the laser light on the measured value of the root mean square slope (RΔq), the window portion 12 is polished to a thickness of 0.1 mm or less, and the arithmetic mean roughness Ra of its surface is preferably 0.005 μm or less.

The average value of the root mean square slope (RΔq) in the roughness curve of the first opposing surface 131 is not limited as long as it is smaller than the average value of the root mean square slope (RΔq) in the roughness curve of the second opposing surface 132. The average value of the root mean square slope (RΔq) in the roughness curve of the first opposing surface 131 may be 0.016 or less (excluding 0). If the average value of the root mean square slope (RΔq) in the roughness curve of the first opposing surface 131 is in such a range, there will be almost no locally large inclined parts. As a result, when it is housed inside the bottomed cylindrical body 1 according to one embodiment, the optical sensor can accurately detect information about the target object.

As long as the average value of the root mean square slope (RΔq) in the roughness curve of the second opposing surface 132 is greater than the average value of the root mean square slope (RΔq) in the roughness curve of the first opposing surface 131, the difference is not limited. For example, the difference between the root mean square slope (RΔq) in the roughness curve of the second opposing surface 132 and the root mean square slope (RΔq) in the roughness curve of the first opposing surface 131 may be, for example, 0.3 or more and 1.5 or less.

The average length (Rsm) and the root mean square slope (RΔq) can be measured in accordance with JIS B 0601:2001 using a shape analysis laser microscope (Keyence Corporation, Ultra-Deep Color 3D Shape Measuring Microscope (VK-X1100 or its successor model)). The measurement conditions are as follows: coaxial illumination, 480x magnification, no cutoff value λs, 0.08mm cutoff value λc, no cutoff value λf, end effect correction, and the measurement range per point from the first opposing surface 131 and the second opposing surface 132 to be measured is set to, for example, 710μm×533μm. For each measurement range, four lines to be measured are drawn along the longitudinal direction of the measurement range, and line roughness measurement is performed. The length of each line to be measured is, for example, 560μm. Three measurement ranges are set on each of the first opposing surface 131 and the second opposing surface 132, and the average length (Rsm) and the root mean square slope (RΔq) are measured from a total of 12 lines. The average values of these measurements are calculated and compared.

The method for manufacturing the bottomed tubular body 1 according to one embodiment is not limited. The bottomed tubular body 1 may be manufactured, for example, by joining one end of the tubular portion 11 so as to seal it with the window portion 12. Examples of such joining methods include diffusion joining, glass joining, and laser welding. When diffusion joining is used as the joining method, excellent chemical resistance is obtained, and the effect of reducing melting of impurities from the vicinity of the joint is also exhibited. Specifically, the bottomed tubular body 1 according to one embodiment is manufactured by the following procedure.

First, one embodiment of a manufacturing method for the cylindrical portion 11 will be described. Aluminum _oxide ( _Al2O3 ) A powder having an average particle size of 0.4 μm to 0.6 μm and aluminum oxide B powder having an average particle size of 1.2 μm to 1.8 μm are prepared. Magnesium hydroxide (Mg(OH) ₂ ) powder is prepared as the Mg source, silicon oxide ( _SiO2 ) powder is prepared as the Si source, and calcium carbonate ( _CaCO3 ) powder is prepared as the Ca source. The silicon oxide powder is prepared as a fine powder having an average particle size of 0.5 μm or less. In the following description, powders other than the aluminum oxide A powder and the aluminum oxide B powder are collectively referred to as the auxiliary component powder.

Next, aluminum oxide A powder and aluminum oxide B powder are weighed out in a mass ratio of 40:60 to 60:40, and the content of Al converted to _Al2O3 is _99.4 mass% or more out of 100 mass% of the components constituting the resulting ceramic, to obtain an aluminum oxide blended powder. For the auxiliary component powder, the Na content in the aluminum oxide blended powder is first determined, and the Na content in the ceramic is converted to _Na2O , and the components constituting the auxiliary component powder (in this example, Si, Ca, Mg, etc.) are weighed out so that the ratio of this converted value to the value converted to oxide is 1.1 or less.

In a total of 100% by mass of the aluminum oxide blend powder and the auxiliary component powder, the content of magnesium hydroxide powder is 0.03% by mass or more and 1.0% by mass or less, the content of silicon oxide powder is 0.02% by mass or more and 2.5% by mass or less, the content of calcium carbonate powder is 0.05% by mass or more and 0.15% by mass or less, and the remainder is aluminum oxide powder and unavoidable impurities. The total content of unavoidable impurities is 0.3% by mass or less.

When obtaining ceramics containing at least any one of elements of Groups 4, 5, and 6 of the periodic table, powders of oxides, nitrates, etc. of these elements may be used. When using oxides of these elements, the content of the oxide powders of the above elements in a total of 100 mass% of the aluminum oxide blend powder and the auxiliary component powder may be 0.01 mass% or more and 1 mass% or less in total.

For a total of 100 parts by mass of the alumina blend powder and the first subcomponent powder, 1 part by mass or more and 1.5 parts by mass or less of a binder such as PVA (polyvinyl alcohol), 100 parts by mass of a solvent, and 0.1 parts by mass or more and 0.55 parts by mass or less of a dispersant are placed in a stirring device and mixed and stirred to obtain a slurry.

After the slurry is sprayed and granulated to obtain granules, a uniaxial press molding device or a cold isostatic press molding device is used to pressurize the granules at a molding pressure of 78 MPa to 128 MPa to obtain a cylindrical molded body. The cylindrical molded body is fired in an air atmosphere at 1500°C to 1700°C for 4 hours to 6 hours to obtain a cylindrical sintered body (cylindrical part 11). The sintered body (cylindrical part 11) obtained by such firing has, for example, an outer diameter of 5.0 mm to 15.0 mm and an inner diameter of 1.0 mm to 13.0 mm, and a length of 30 mm to 150 mm in the axial direction. In particular, the firing temperature is preferably 1600°C to 1650°C. The inner and outer wall surfaces of the obtained sintered body (cylindrical part 11) may be polished or ground as necessary.

The end face (second opposing surface 132) of the cylindrical portion 11 that comes into contact with the window portion 12 is processed so that the average value of the average length (Rsm) in the roughness curve is smaller than that of the end face (first opposing surface 131) of the window portion 12 that comes into contact with the cylindrical portion 11. If the average value of the average length (Rsm) in the roughness curve of the second opposing surface 132 is smaller than the average value of the average length (Rsm) in the roughness curve of the first opposing surface 131 in the unprocessed state, processing is not necessary. This processing is polishing, grinding, etc., and is performed as necessary. When polishing, a slurry containing diamond having an average particle size of 0.5 μm or more and 3 μm or less may be supplied to a lapping machine made of copper, tin, or tin-lead alloy at predetermined intervals to polish.

Next, one embodiment of a method for manufacturing the window portion 12 will be described. First, a sapphire ingot grown by the Edge-defined film-fed Growth (EFG) method, the Czochralski method (CZ) method, the Chiroporus method, or the like is cut using a multi-wire saw so that the c-plane becomes the main surface.

For example, the sapphire ingot is cut into a disk shape having a diameter of 5.0 mm to 15.0 mm and a thickness of 0.2 mm to 2.0 mm, and the window portion 12 is obtained without being polished or ground. The sapphire ingot may contain at least one of Mg, Si, and Ca, each of which has a content of 10 mass ppm or less. When the sapphire ingot contains Mg, Si, and Ca, the content of each of these elements may be determined using a glow discharge mass spectrometer (GDMS).

The end face (first opposing surface 131) of the window portion 12 that comes into contact with the cylindrical portion 11 is processed so that the average value of the average length (Rsm) in the roughness curve is longer than the end face (second opposing surface 132) of the cylindrical portion 11 that comes into contact with the window portion 12. If the average value of the average length (Rsm) in the roughness curve of the first opposing surface 131 in the unprocessed state is greater than the average value of the average length (Rsm) in the roughness curve of the second opposing surface 132, no processing is required. This processing is polishing, grinding, etc., and is performed as necessary.

When polishing, a slurry containing diamonds having an average particle size of 0.5 μm or more and 3 μm or less may be supplied to a lapping machine made of copper, tin, or tin-lead alloy at predetermined intervals to perform polishing. When polishing both end faces, the average particle size of diamonds used to polish the end face of the window portion 12 that comes into contact with the cylindrical portion 11 may be smaller than the average particle size of diamonds used to polish the end face of the cylindrical portion 11 that comes into contact with the window portion 12.

Furthermore, both end faces of the window portion 12 may be subjected to CMP (Chemical Mechanical Polishing) polishing using colloidal silica. By subjecting both end faces of the window portion 12 to CMP polishing, the light transmittance of the window portion 12 can be further improved.

Next, the cylindrical portion 11 and the window portion 12 are joined so as to seal one end of the cylindrical portion 11. The joining method is not limited, and examples include diffusion bonding. The method of joining by diffusion bonding is described below.

First, water is applied to at least one of the second opposing surface 132 of the cylindrical portion 11 and the first opposing surface 131 of the window portion 12. There are no limitations on the method of applying water, and examples of the method include spraying water on at least one of the first opposing surface 131 and the second opposing surface 132, applying water with a brush, or directly immersing the surface in water.

The attached water brings the opposing surfaces into close contact with each other due to surface tension. Furthermore, elements other than Al (Si, Mg, Ca, etc.) induced by a hydration reaction (local hydrolysis reaction of OH groups by _H2O with few impurities) are recrystallized with aluminum oxide due to differences in electronegativity, resulting in strong bonding. The water can be, for example, pure water or ultrapure water such as distilled water, RO water (reverse osmosis water), ion-exchanged water, or Elix water (registered trademark of Merck Ltd.).

After the water is absorbed, the cylindrical portion 11 and the window portion 12 are adsorbed and pressed from the longitudinal direction with a pressure of, for example, 800 gf to 3 kgf, and then heat treated at 1000°C to 1800°C for 4 hours to 6 hours. In this way, a bottomed cylindrical body 1 according to one embodiment is obtained.

A number of bottomed cylindrical bodies 1 were produced, and the average length (Rsm) of the roughness curve of the first opposing surface 131 and the average length (Rsm) of the roughness curve of the second opposing surface 132 were measured for each bottomed cylindrical body 1. The average of the measurements of the first opposing surface 131 was 24.29 μm, and the average of the measurements of the second opposing surface 132 was 15.22 μm.

Furthermore, the root mean square slope (RΔq) of the roughness curve of the first opposing surface 131 and the root mean square slope (RΔq) of the roughness curve of the second opposing surface 132 were also measured. The average of the measured values of the first opposing surface 131 was 0.004, and the average of the measured values of the second opposing surface 132 was 0.694. The average values of the average length (Rsm) and the root mean square slope (RΔq) were obtained by the measurement method described above.

The bottomed cylindrical body according to the present disclosure is used, for example, as a seal assembly for an optical sensor, a high-brightness light-emitting device, an analytical device, a fuel injection device, an ultraviolet illuminometer, an infrared detection device, a plasma processing device, etc. When the bottomed cylindrical body according to the present disclosure is used, for example, as a seal assembly for an optical sensor, it is possible to accurately detect information about an object even in an environment where it is exposed to high temperatures for a long period of time.

The bottomed tubular body according to the present disclosure is not limited to the above-described embodiment or other embodiments. For example, the bottomed tubular body 1 described above has a tubular portion 11 that is cylindrical. However, the tubular portion is not limited to a cylindrical shape, and may be, for example, an elliptical tubular shape, or may have a cross section that is a polygonal tubular shape such as a triangular, rectangular, pentagonal, or hexagonal shape, depending on the application of the bottomed tubular body.

For example, in the above-mentioned bottomed cylindrical body 1, the cylindrical portion 11 and the window portion 12 are joined so as to seal only one end of the cylindrical portion 11. However, in the bottomed cylindrical body according to the present disclosure, the cylindrical portion and the window portion may be joined so as to seal both ends of the cylindrical portion.

1 Bottomed Cylindrical Body 11 Cylindrical Part 12 Window Part 13 Opposing Surface 131 First Opposing Surface 132 Second Opposing Surface

Claims (12)

The device includes a cylindrical portion formed of ceramics containing aluminum oxide as a main component, and a flat plate-shaped window portion that seals at least one end of the cylindrical portion,
The window is made of sapphire or a transparent ceramic,
a joint between the cylindrical portion and the window portion,
a first opposing surface of the window portion on the cylindrical portion side has a larger average value of a mean length (Rsm) in a roughness curve than a second opposing surface of the cylindrical portion on the window portion side;
A cylindrical body with a bottom. A cylindrical body with a bottom as described in claim 1, wherein the average value of the average length (Rsm) in the roughness curve of the second opposing surface is 22.8 μm or less (excluding 0 μm). The bottomed cylindrical body described in claim 1 or 2, wherein the second opposing surface has a larger average value of the root mean square slope (RΔq) in the roughness curve than the first opposing surface. A cylindrical body with a bottom as described in any one of claims 1 to 3, wherein the average value of the root mean square slope (RΔq) in the roughness curve of the first opposing surface is 0.016 or less (excluding 0). the ceramic forming the cylindrical portion further contains sodium;
In the grain boundary phase, at least a portion of the sodium is present as sodium oxide (Na ₂ O);
5. The bottomed tubular body according to claim 1, wherein sodium oxide (Na ₂ O) is present in a larger amount in the inner region than in the boundary region with the aluminum oxide crystals. 6. The bottomed tubular body according to claim 5, wherein the ceramic forming the tubular portion contains sodium in a ratio of 30 ppm by mass to 500 ppm by mass, calculated as sodium oxide ( _Na2O ). A bottomed cylindrical body as described in any one of claims 1 to 6, wherein the ceramic forming the cylindrical portion further contains nickel in a proportion of 4 ppm by mass or less, calculated as nickel oxide (NiO). A bottomed cylindrical body according to any one of claims 1 to 7, wherein the ceramic forming the cylindrical portion contains at least one element from Groups 4, 5, and 6 of the periodic table in a total amount of 0.01% by mass or more and 1% by mass or less, calculated as an oxide. A bottomed cylindrical body as described in any one of claims 1 to 8, wherein the ceramic forming the cylindrical portion contains magnesium in a proportion of 0.02 mass% or more and 0.7 mass% or less, calculated as magnesium oxide (MgO). A bottomed cylindrical body as described in any one of claims 1 to 9, wherein the window portion is formed of sapphire and the c-axis of the sapphire and the central axis of the cylindrical portion are approximately parallel. A bottomed cylindrical body as described in any one of claims 1 to 10, wherein the first opposing surface and the second opposing surface are diffusion bonded. A seal assembly for an optical sensor comprising a bottomed cylindrical body according to any one of claims 1 to 11.

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